Mental Capacity Act 2005 in England

The Law That Governs Every Decision About Your Parent

The Mental Capacity Act 2005 (MCA) is the statute that determines who can make decisions for an adult who cannot make them for themselves. If your parent has dementia, has suffered a stroke, or has any condition affecting their cognitive function, this Act controls every legal and medical decision made on their behalf — from whether they can sign a Lasting Power of Attorney to where they live and what medical treatment they receive.

Understanding the MCA matters because it cuts both ways. It protects your parent from having decisions taken away prematurely, and it gives you a legal framework to step in when they genuinely cannot decide for themselves. Hospitals, local authorities, banks, and care homes all operate within this framework, and they will invoke it whether or not you understand it.

The Five Statutory Principles

The MCA opens with five principles that every professional — and every family member acting as attorney or deputy — must follow. These are not suggestions; they are legal requirements.

1. Assume capacity until proved otherwise. Your parent is presumed to have mental capacity. A diagnosis of dementia, a hospital admission, or age alone does not override this presumption. Anyone who claims a person lacks capacity must demonstrate it.

2. Support the person to make their own decisions first. Before concluding that your parent cannot decide, you must take practical steps to help them. That means choosing the right time of day (many people with dementia are clearer in the morning), using simple language, providing written information they can review, and removing distractions.

3. An unwise decision is not proof of incapacity. Your parent can make decisions you disagree with — refusing a care home placement, spending money on things you consider wasteful, declining medical treatment — and that does not mean they lack capacity. The Act protects the right to make choices others consider unwise.

4. Act in the person's best interests. When someone is assessed as lacking capacity for a specific decision, any decision made on their behalf must serve their best interests, not the convenience or preferences of the family or professionals.

5. Choose the least restrictive option. If there are multiple ways to achieve the same outcome, choose the one that interferes least with the person's rights and freedom.

The Four-Part Capacity Test

When there is a genuine reason to question whether your parent can make a particular decision, the MCA provides a two-stage test:

Stage 1 — Is there an impairment of, or disturbance in the functioning of, the mind or brain? This could be dementia, a brain injury, a stroke, delirium, or the effects of medication. The impairment does not need to be permanent.

Stage 2 — Does that impairment mean the person cannot make the specific decision? This is assessed against four functional criteria. The person must be able to:

1. Understand the information relevant to the decision, including the consequences
2. Retain that information long enough to make the decision (even briefly is sufficient)
3. Use or weigh the information as part of the decision-making process
4. Communicate the decision by any means — speech, writing, sign language, blinking

A person fails the capacity test only if they cannot do one or more of these four things because of the impairment identified in Stage 1. Difficulty is not the same as inability.

How Capacity Applies to Making an LPA

A common misconception is that a dementia diagnosis closes the door on making a Lasting Power of Attorney. It does not. Capacity under the MCA is decision-specific and time-specific. Your parent might lack the capacity to manage complex investments but still have the capacity to understand what an LPA is, who they are appointing, and what powers they are granting.

The capacity threshold for making an LPA is relatively low compared to other decisions. The donor needs to understand:

• What an LPA is and what authority it gives the attorney
• Who they are appointing and why they trust that person
• That the LPA can be used when they lose capacity (and, for Property and Financial Affairs, potentially while they still have it)
• That they can add restrictions and conditions

If there is any doubt about whether your parent has capacity to make an LPA, arrange a formal capacity assessment with their GP or a specialist. This typically costs £200 to £500. The GP completes a medical opinion confirming the person understood the decision at the time they signed. This evidence protects the LPA from being challenged later — a challenge that could void the document entirely and force you into a deputyship application costing upwards of £1,200 in court and supervision fees.

Fluctuating Capacity

Many conditions — early-to-moderate dementia, delirium during a hospital stay, the effects of certain medications — cause capacity to fluctuate. Your parent might understand a decision clearly on Tuesday morning and be unable to engage with it on Wednesday afternoon.

The MCA accounts for this. If a decision can wait until a period of better capacity, it should. For an LPA, this means scheduling the signing for a time when the donor is typically most alert, ensuring the certificate provider meets with them during that window, and having the GP assessment done during a clear period.

Fluctuating capacity also affects how attorneys exercise their authority. A Health and Welfare LPA can only be used when the donor lacks capacity for the specific decision at hand. If your parent has a clear day and can express a preference about their daily routine or a medical appointment, the attorney must defer to them — the LPA does not override their autonomy during periods of capacity.

Best Interests Decisions Under Section 4

When your parent lacks capacity for a specific decision, whoever makes it on their behalf — whether that is you as attorney, a deputy, a doctor, or a social worker — must follow the best interests checklist in Section 4 of the Act:

• Consider whether the person is likely to regain capacity, and whether the decision can wait
• Involve the person as fully as possible in the decision
• Consider their past and present wishes, feelings, beliefs, and values
• Consult anyone named by the person, their carers, and other interested parties
• Do not make the decision based on the person's age, appearance, or assumptions about their condition

The best interests test is not a vote. It does not mean asking the family what they want and going with the majority. It means weighing everything known about what the person themselves would have wanted, informed by the people who know them best.

Why This Matters for Your Family

Every significant eldercare decision in England — arranging a care needs assessment, choosing a care home, selling the family home, accessing bank accounts, contesting an NHS Continuing Healthcare decision — runs through the Mental Capacity Act. Understanding the capacity test and the best interests framework gives you the language and the legal standing to advocate for your parent in meetings with social workers, hospital discharge teams, and local authority assessors.

The England Lasting Power of Attorney & Deputyship Kit includes a capacity assessment preparation guide, the best interests checklist adapted for family use, and the Section 7 preference templates that let your parent's wishes carry legal weight even after they lose the ability to express them directly.

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